1. Field of the Invention
The present invention relates to a dynamic power control method and circuit thereof, and more particularly, to a dynamic power control method and circuit thereof capable of dynamically adjusting supply voltages of an amplifier according to differences between an output signal of the amplifier and supply voltages of the amplifier.
2. Description of the Prior Art
Amplifiers are basic circuit components frequently used in the analog integrate circuit. Generally, supply voltages of an amplifier is fixed to a maximum voltage for maximizing the input dynamic range and the output dynamic range of the amplifier, such that the amplifier can undistortedly convert an input signal with maximum swing to an output signal. The amplifier generates huge operational current when the supply voltage is designed to the maximum voltage. However, the amplifier may need less operational current for processing the input signal with small swing. In such a condition, the most part of the operational current becomes idle current that results in unnecessary power consumption. In other words, if the supply voltage of the amplifier is set to the maximum voltage, the efficiency of the amplifier is significantly decreased.
The prior art utilizes an input signal detection circuit for detecting the swing of the input signal, to appropriately adjust the supply voltages of the amplifier. The unnecessary power consumption can be therefore avoided. However, except for detecting the swing of the input signal, the input signal detection circuit needs to detect the structure and the gain of the amplifier for accurately adjusting the supply voltage, to achieve the goal of generating undistorted output signal. In other words, the input signal detection circuit needs to be modified when the structure or the gain of the amplifier is changed according to different applications. The design flow of the amplifier is therefore complicated and the cost of the amplifier is increased. Thus, there is a need for improving the prior art.